The Yalu River Estuary National Wetland Nature Reserve is the last stopover area for migratory shorebirds flying north on the East Asian-Australasian and West Pacific flyways. Each year, more than 500,000 migratory shorebirds stop here to rest and forage, especially wading birds on the East Asia-Australian flyway. Long-distance migratory waders need to accumulate energy rapidly at stopover sites to ensure successful migration and reproduction. They mainly rely on polychaetes, bivalves, gastropods and crustaceans on the intertidal zone as a food source to renew their energy reserves. Human activities directly impact intertidal biological communities. Hydropower, human-caused changes to the physicochemical environment, sediments and other ecological factors influence the stability of ecological systems like estuaries and the energy supply available to birds at stopover sites. From March 2010 to June 2011, an ecological investigation was conducted on the Yalu River estuary wetland. The results show that the structure of biological community is relatively simple, dominated by bivalves, gastropods and polychaetes, and these dominant species have obviously undergone ecological succession. The estuary has low species diversity, and the species have low density populations. The wading birds forage on relatively poor sources of energy, while the biomass of the forage species renews slowly and provides a comparatively low level of energy. Moerella jedoensis, Cyclina sinensis (larva) and Glycera chirori are the main food species. The food organisms in the low tidal areas are significantly impacted by the migratory birds, especially M. jedoensis, because the foraging activities of wading birds are mainly concentrated on the low tidal areas during the peak of the northward migration. Bullacta exarata, thought to be the dominant species with the widest ecological distribution and distributed across the entire study area and tidal zone, is excluded by the waders as a food source since they excrete toxic mucus on their body surface. The food organisms are capable of recovering their former abundance and biomass after the peak period of the wading bird migration. The intertidal biological community structure has obviously undergone succession in the past 30 years as a result of human-caused changes. The dominant species with the widest niche breadth, B. exarata, is distributed throughout the area of investigation and its cross-sections and tidal zone, but its surface secretes toxic mucus making it inedible to the wading birds. This succession has reduced the food sources and energy available to wading birds as the non-food organisms gradually replaced food organisms. If the wading birds do not obtain enough energy during migration, the success rate of their spring migration will gradually decline, creating a threat to the continued survival of some populations. The disappearance of specific food organisms may also accelerate the rate of extinction for some endangered waders. Large-scale reclamation and coastal engineering from the 1960s to the 1990s resulted in a serious loss of habitat and in structural damage to tidal communities in the high and middle tide belts. This caused some species to disappear or to be forced to move to the subtidal zone. Also, ponds and beach farming have long been using drugs to eliminate organisms harmful to shellfish, which has inadvertently significantly reduced the number of beach species. Frequent disturbance of the substrate in the estuary and the deposition of fine sandy sediments are additional factors in the decline of zoobenthos populations. Finally, while humans were not observed to cause direct significant threats to wading birds, all components of the ecological system, including human, must be considered to harmoniously preserve the integrity of Yalu River estuary wetland ecosystem while maintaining sustainable development for society and human economic concerns.